Zi Collection, Page Position: Upper. Radical: Strike (pū). Page 245, Entry 12. Guangyun and Jiyun dictionaries indicate the pronunciation as ku (falling tone), which is the same as the sound for the word meaning cave. The terms ku-gu and gu-ku denote instability. The Leipian dictionary defines gu-ku as referring to a lack of smoothness in movement. It is also written in a variant form. The character was originally written with the radical for strike.